The utilization of intramedullary nails or rods in the treatment of bone fractures is well known in the art. Furthermore, a number of prior art intramedullary nail systems comprise intramedullary nails provided with holes therethrough adjacent the proximal and distal ends for insertion of locking screws. Depending upon the severity of the fracture, the intramedullary nail may be implanted without locking screws, with at least one locking screw either proximally or distally (known as either partial or dynamic locking) or with at least one locking screw both proximally and distally (known as either complete or static locking).
Static locking neutralizes rotational stresses while preventing shortening of the limb. Dynamic locking neutralizes rotational stresses on one side of the fracture site while permitting axial loading. A static locking condition may be converted into a dynamic locking condition by removing either the proximal or distal screws, thereby permitting axial loading. Both a dynamic locking condition and static locking condition may be converted into an unlocked condition by removing all locking screws, thereby allowing rotational stresses across the fracture site and allowing axial loading of the fracture site.
When properly permitted, rotational stresses and axial loading, combined with patient weightbearing, enhances the healing process. However, the removal of the locking screws has the severely adverse effect of permitting the intramedullary nail to migrate or back out of the intramedullary canal.
Prior art devices for treating a bone fracture further include plates with holes therethrough for screws to be inserted. These plates are designed to impart compressive forces on the fracture site. A plate, known as a tension band plate, may be applied to one side of the fractured bone with a tension device, and secured with a number of screws which are inserted through the bone and which firmly attach the plate. A tension band plate applies compressive forces to the fracture site and resists rotational stress.
In some round bones there is not enough room to apply the tension device. In such instances a semi-tubular plate with oval holes therethrough for screws to be inserted may be utilized. When screwed firmly to the bone, the edges of the semi-tubular plate press into the cortex and resist rotation. When screws are inserted eccentrically at one end of the oval, the plate is placed under tension as the spherical head of the screw engages the plate. Standard size prior art semi-tubular plates, for example, are made with oval holes which accept a single 4.5 mm cortex screw, while small plates accept one 3.5 mm cortex screw. Semi-tubular plates may be bent and twisted so as to fit the fractured bone. If it is necessary to use more than one plate, they can be applied adjacent one another but without any cooperating engagement between them.
Further detail review of such prior art devices are presented in the following publications which are incorporated herein: "The Grosse & Kempf.TM. Intramedullary Nailing System", Howmedica, Inc., 1983 and 1984; Boyle, Marc, M.D., "Howmedica.TM. Surgical Techniques--Grosse & Kempf.TM. Surgical Technique", Howmedica, Inc., 1984; "Russell-Taylor Tibial Interlocking Nail Systems", Richards; "Brooker Tibial System" and "Brooker Tibial Nail Surgical Technique", Biomet Inc.; "Howmedica Quality Systems, The Howmedica ICS.TM. Stainless Steel Compression Systems", Howmedica, Inc., 1980; Ramon B. Gustilo, M.D. and Michael W. Chapman, M.D., "Orthopedic Surgery Viewpoints '83, Management of Type III Open Fractures", Eli Lilly and Company; "ECT European Compression Technique, Internal Fracture Fixation Reference Manual", Zimmer, Inc.; "Osteo Auto-Compression Plating System Catalog", Richards Medical Company, 1985; "ORIF", DePuy, Inc., 1986; "Introducing Two New Small Bone Sets From Synthes", Synthes Ltd., 1986; and "ASIF Technique", Synthes Ltd.